A person with a flat chest, i.e., without breasts.
A navel that is neither protruding nor sunken.
A flatmate.
A flat-bottomed sloop-rigged sharpie.
The operator of a flat joint, or crooked gambling operation.
A flat earther.
A traditional two-dimensional motion picture, as opposed to a deepie.
A flat white (type of coffee).
A flattie spider.
A flat-coated retriever.
A flat store.
A flat marinated cut of meat.
Someone with an untidy appearance.
The back of the neck, nape; also scruff of the neck.
The loose skin at the back of the neck of some animals.
Stubble, facial hair (on males).
To lift or carry by the scruff.